X-Ray-Based 3D Histopathology of the Kidney Using Cryogenic Contrast-Enhanced MicroCT.

The kidney's microstructure, which comprises a highly convoluted tubular and vascular network, can only be partially revealed using classical 2D histology. Considering that the kidney's microstructure is closely related to its function and is often affected by pathologies, there is a need for powerful and high-resolution 3D imaging techniques to visualize the microstructure. Here, we present how cryogenic contrast-enhanced microCT (cryo-CECT) allowed 3D visualization of glomeruli, tubuli, and vasculature. By comparing different contrast-enhancing staining agents and freezing protocols, we found that the preferred sample preparation protocol was the combination of staining with 1:2 hafnium(IV)-substituted Wells-Dawson polyoxometalate and freezing by submersion in isopentane at -78°C. This optimized protocol showed to be highly sensitive, allowing to detect small pathology-induced microstructural changes in a mouse model of mild trauma-related acute kidney injury after thorax trauma and hemorrhagic shock. In summary, we demonstrated that cryo-CECT is an effective 3D histopathological tool that allows to enhance our understanding of kidney tissue microstructure and their related function.

Internal and interfacial microstructure characterization of ice droplets on surfaces by X-ray computed tomography.

HYPOTHESIS: Characterizing the microstructure of an ice/surface interface and its effect on the icephobic behavior of surfaces remains a significant challenge. Introducing X-ray Computed Tomography (XCT) can provide unprecedented insights into the internal (porosity) and interfacial structures, i.e. wetting regime, between (super)hydrophobic surfaces and ice by visualizing these optically inaccessible regions. EXPERIMENTS: Frozen droplets with controlled volume were deposited on top of metallic and polymeric substrates with different levels of wettability. Different modes of XCT (3D and 4D) were utilized to obtain information on the internal and interfacial structure of the ice/surface system. The results were supplemented by conventional surface analysis techniques, including optical profilometry and contact angle measurements. FINDINGS: Using XCT on ice/surface systems, the 3D and 4D (imaging with temporal resolution) structural information can be visualized. From these datasets, qualitative and quantitative results were obtained, not only for characterizing the interface but also for analyzing the entire droplet/surface system, e.g., measurement of porosity size, shape, and location. These results highlight the potential of XCT in the characterization of both droplets and substrates and proves that the technique can aid to develop hydrophobic surfaces for use as icephobic materials.

Cryogenic contrast-enhanced microCT enables nondestructive 3D quantitative histopathology of soft biological tissues.

Biological tissues comprise a spatially complex structure, composition and organization at the microscale, named the microstructure. Given the close structure-function relationships in tissues, structural characterization is essential to fully understand the functioning of healthy and pathological tissues, as well as the impact of possible treatments. Here, we present a nondestructive imaging approach to perform quantitative 3D histo(patho)logy of biological tissues, termed Cryogenic Contrast-Enhanced MicroCT (cryo-CECT). By combining sample staining, using an X-ray contrast-enhancing staining agent, with freezing the sample at the optimal freezing rate, cryo-CECT enables 3D visualization and structural analysis of individual tissue constituents, such as muscle and collagen fibers. We applied cryo-CECT on murine hearts subjected to pressure overload following transverse aortic constriction surgery. Cryo-CECT allowed to analyze, in an unprecedented manner, the orientation and diameter of the individual muscle fibers in the entire heart, as well as the 3D localization of fibrotic regions within the myocardial layers. We foresee further applications of cryo-CECT in the optimization of tissue/food preservation and donor banking, showing that cryo-CECT also has clinical and industrial potential.

Development and characterization of a rat brain metastatic tumor model by multiparametric magnetic resonance imaging and histomorphology.

To facilitate the development of new brain metastasis (BM) treatment, an easy-to-use and clinically relevant animal model with imaging platform is needed. Rhabdomyosarcoma BM was induced in WAG/Rij rats. Post-implantation surveillance and characterizations were systematically performed with multiparametric MRI including 3D T1 and T2 weighted imaging, diffusion-weighted imaging (DWI), T1 and T2 mapping, and perfusion-weighted imaging (PWI), which were validated by postmortem digital radiography (DR), µCT angiography and histopathology. The translational potential was exemplified by the application of a vascular disrupting agent (VDA). BM was successfully induced in most rats of both genders (18/20). Multiparametric MRI revealed significantly higher T2 value, pre-contrast-enhanced (preCE) T1 value, DWI-derived apparent diffusion coefficient (ADC) and CE ratio, but a lower post-contrast-enhanced (postCE) T1 value in BM lesions than in adjacent brain (p < 0.01). PWI showed the dynamic and higher contrast agent uptake in the BM compared with the adjacent brain. DR, µCT and histopathology characterized the BM as hypervascular tumors. After VDA treatment, the BM showed drug-related perfusion changes and partial necrosis as evidenced by anatomical, functional MRI parameters and postmortem findings. The present BM model and imaging modalities represent a feasible and translational platform for developing BM-targeting therapeutics.

A dataset of micro-scale tomograms of unidirectional glass fiber/epoxy and carbon fiber/epoxy composites acquired via synchrotron computed tomography during in-situ tensile loading.

We have performed synchrotron computed tomography on two different fiber-reinforced composites while they were being continuously in-situ loaded in 0° tension. One material is a glass/epoxy laminate and the other is a carbon/epoxy laminate. The voxel size is 1.1 µm, which allows clear recognition of the glass fibers, but not distinct individual carbon fibers. For each material, four loading steps are selected with approximately 0, 40, 73, and 95% of the failure load, and the 3D images of the four volumes from each material are overlaid. A volume of interest in the middle 0° ply is chosen and located in the 3D image of each loading step (Fig. 1). The cropped volumes of interest for each material are presented in this publication and are publicly available on Mendeley Data[1]. As examples of two frequently-used type of unidirectional fiber-reinforced composites, the presented data can be used for different microstructural analyses, including investigation of the 3D variability in fiber distribution and orientation, and their evolution during tensile loading. For example, we have performed fiber orientation analysis on this data, using our digital image correlation-based technique, in [2]. Moreover, real-time formation of fiber breaks with tensile loading can be investigated in the data.

Is Hypoxia Related to External Cervical Resorption? A Case Report.

Despite the fact that external cervical resorption (ECR) is a well-known and rather frequently met condition, the driving force of this phenomenon still remains unclear. Recently, hypoxia has been linked to ECR. Thus, the aim of this work was to investigate the existence of hypoxia in ECR and hypothesize on its role at the time of extraction. This work is a case study of a tooth with ECR. ECR diagnosis was based on clinical and radiographic examination with cone-beam computed tomographic imaging. The extracted tooth was further analyzed by using nanofocus computed tomographic imaging and immunohistology. To investigate the 3-dimensional extent and pattern of ECR, in vivo cone-beam computed tomographic imaging and ex vivo nanofocus computed tomographic imaging were used. Different histologic stains were used to investigate the presence of a hypoxic environment and to gain a better insight into the involved cells, neuronal structures, and remodeling process during ECR. A higher distribution of hypoxia-inducible factor 1a-positive cells was found in the apical part of the resorption area when compared with the coronal area of the resorption. In addition, a similar distribution of hypoxia-inducible factor 1a-positive odontoblasts was observed in the pulp. Three-dimensional analysis of the calcification of the pulp revealed the formation of pulp stones in areas with higher hypoxia. Histology showed that remodeling during ECR can occur according to a layered pattern. This investigation confirms the presence of hypoxia in ECR and shows that there is a gradient of hypoxia within the ECR lesion and surrounding tooth structure. The hypoxic environment within the pulp is also indicated by the formation of pulp stones.

Right ventricle outflow tract prestenting: In vitro testing of rigidity and corrosion properties.

BACKGROUND: The aim of this study was to assess the resistance to compression (stiffness) of frequently used stents for right ventricular outflow tract prestenting. In addition, to assess the corrosion potential when different types of stent alloys come into contact with each other. METHOD: Different stents were tested in vitro in various combinations at specialized metallurgic laboratories. A bench compression test was used to assess resistance to compression of singular and joined combinations of stents. Corrosion was evaluated by standardized electrochemical galvanic tests in physiological solutions at 37°C. Single stents and combinations of stents were evaluated over a period of 4-12 weeks. RESULTS: Relative stiffness of the stents Optimus/Andrastent XXL/Intrastent LD Max/8zig Cheatham-Platinum, expressed as load per length to deform the stent for 1 mm at 22 mm was 100/104/161/190. Adding additional stents to a single stent significantly strengthened the joined couples (P < 0.001). The lowest galvanic corrosion rates (about 0.000001 mm/year) were observed for the joined CP-Andrastent, Andra-Sapien, and Andra-SapienXT. The corrosion rate for coupled CP-Sapien and CP-SapienXT was somewhat higher (about 0.000003 mm/year). The materials with the highest corrosion rates resulted in material losses of, respectively, 17 and 24 µg/year, which is negligible over a lifetime. CONCLUSION: Adding stents to a single stent significantly increases stiffness which will reduce the risk of metal fatigue failure. Corrosion of individual stents or stent combinations occurs, but is negligible over a human lifetime with low risk of biological effects. No mechanical integrity problems are thus expected as there is only 0.3% of the initial diameter of the struts of a stent that will be lost as a consequence of corrosion after 100 years.

CoCr F75 scaffolds produced by additive manufacturing: Influence of chemical etching on powder removal and mechanical performance.

Additive manufacturing techniques such as Selective Laser Melting (SLM) allow carefully controlled production of complex porous structures such as scaffolds. These advanced structures can offer many interesting advantages over conventionally produced products in terms of biological response and patient specific design. The surface finish of AM parts is often poor because of the layer wise nature of the process and adhering particles. Loosening of these particles after implantation should be avoided, as this could put the patient's health at risk. In this study the use of hydrochloric acid and hydrogen peroxide mixtures for surface treatment of cobalt-chromium F75 scaffolds produced by SLM is investigated. A 27% HCl and 8% H2O2 etchant proved effective in removing adhering particles while retaining the quasi-static and fatigue performance of the scaffolds.

Modeling the dose dependence of the vis-absorption spectrum of EBT3 GafChromic™ films.

PURPOSE: The aim of this work was to model the dose dependence of the darkening of GafChromic™ EBT3 films by combining the optical properties of the polydiacetylene polymer phases, and a modified version of the single-hit model, which will take the stick-like shape of the monomer microcrystals into account. Second, a comparison is made between the quantification of the film darkening by flatbed scanning and by UV-vis absorption spectroscopy. METHOD: GafChromicTM EBT3 films were irradiated with a 6 MV photon beam at dose levels between 0 and 50 Gy. The radiation-induced darkening of the films is quantified by a flatbed scanner, and by UV-vis absorption spectroscopy in the wavelength range of 220-750 nm. From the UV-vis absorption spectra, the contribution of each polymer phase to the absorbance was deduced. Next, the dose dependence of the polymer content is described by a modified single-hit model where the size distribution of polymerizable centers is approximated by way of the size distribution of the monomer microcrystals in the film. RESULTS: The absorption properties of the film can be accurately quantified by UV-vis spectroscopy for dose levels between 0 and 10 Gy. Over 10 Gy, the absorption spectrum saturates due to the limited sensitivity of the spectrometer. The modified single-hit model was successful in describing the increasing polymer concentration with radiation dose, using a log-normal distribution for the length of the stick-like monomer microcrystals. The dose dependence of the polymer content, deduced from the UV-vis absorption spectrum, differs from that of the flatbed scanning method and is more sensitive to changes in dose. CONCLUSION: The dose dependence of the polymer concentration can be modeled by taking into account the distribution of active centers using the microstructure of the active layer for dose levels between 0 and 10 Gy. The dissimilar dose dependence of the polymer concentration and the absorbance must be accounted for when modeling darkening from the kinetics of the photopolymerization reaction.

CoCr F75 scaffolds produced by additive manufacturing: Influence of chemical etching on powder removal and mechanical performance.

Additive manufacturing techniques such as Selective Laser Melting (SLM) allow carefully controlled production of complex porous structures such as scaffolds. These advanced structures can offer many interesting advantages over conventionally produced products in terms of biological response and patient specific design. The surface finish of AM parts is often poor because of the layer wise nature of the process and adhering particles. Loosening of these particles after implantation should be avoided, as this could put the patient's health at risk. In this study the use of hydrochloric acid and hydrogen peroxide mixtures for surface treatment of cobalt-chromium F75 scaffolds produced by SLM is investigated. A 27% HCl and 8% H2O2 etchant proved effective in removing adhering particles while retaining the quasi-static and fatigue performance of the scaffolds.

Strain development in bulk-filled cavities of different depths characterized using a non-destructive acoustic emission approach.

OBJECTIVES: (1) To evaluate the effect of cavity depth and composite type on the interfacial debonding in bulk-filled cavities. (2) To correlate the theoretical shrinkage stress and the level of interfacial debonding determined by acoustic emission (AE). METHODS: 80 sound molars were divided in two groups to receive a Class-I cavity (3.5×3.5mm) with 2.5- or 4.0-mm depth. The cavities were restored with either a conventional paste-like (Filtek Z100, 3M ESPE), a conventional flowable (G-ænial Universal Flo, GC), a bulk-fill paste-like (Tetric EvoCeram Bulk Fill, Ivoclar Vivadent) or a bulk-fill flowable (SDR, Dentsply) composite (n=10). AE signals were recorded from the start of curing for 20min. The cumulative number of AE events was correlated with the theoretical maximum shrinkage stress induced by each composite. Two samples from each group were scanned using micro-computed tomography (µCT) and qualitatively evaluated. RESULTS: Both composite type and cavity depth had a significant influence on the number of AE. The conventional paste-like composite generated significantly more AE than the other composites. The AE number increased sigmoidally in function of time, with a more rapid increase after a few seconds for the conventional composites than for the bulk-fill composites. A strong linear correlation was found between the predicted shrinkage stress values and the total number of AE events for both cavities depth. Representative µCT images showed larger de-bonding areas for 4.0-mm cavities and for conventional composites. SIGNIFICANCE: Premature interfacial or cohesive cracks can already develop during placement/curing of the composite. This might compromise the restoration integrity and in turn affect its survival in the long term. The amount AE events increased linearly with the theoretical maximum shrinkage stress of the composites.

Understanding External Cervical Resorption in Vital Teeth.

INTRODUCTION: The aim of this study was to investigate the 3-dimensional (3D) structure and the cellular and tissue characteristics of external cervical resorption (ECR) in vital teeth and to understand the phenomenon of ECR by combining histomorphological and radiographic findings. METHODS: Twenty-seven cases of vital permanent teeth displaying ECR were investigated. ECR diagnosis was based on clinical and radiographic examination with cone-beam computed tomographic imaging. The extracted teeth were further analyzed by using nanofocus computed tomographic imaging, hard tissue histology, and scanning electron microscopy. RESULTS: All examined teeth showed some common characteristics. Based on the clinical and experimental findings, a 3-stage mechanism of ECR was proposed. At the first stage (ie, the initiation stage), ECR was initiated at the cementum below the gingival epithelial attachment. At the second stage (ie, the resorption stage), the resorption invaded the tooth structure 3-dimensionally toward the pulp space. However, it did not penetrate the pulp space because of the presence of a pericanalar resorption-resistant sheet. This layer was observed to consist of predentin, dentin, and occasionally reparative mineralized (bonelike) tissue, having a fluctuating thickness averaging 210 µm. At the last advanced stage (ie, the repair stage), repair took place by an ingrowth and apposition of bonelike tissue into the resorption cavity. During the reparative stage, repair and remodeling phenomena evolve simultaneously, whereas both resorption and reparative stages progress in parallel at different areas of the tooth. CONCLUSIONS: ECR is a dynamic and complex condition that involves periodontal and endodontic tissues. Using clinical, histologic, radiographic, and scanning microscopic analysis, a better understanding of the evolution of ECR is possible. Based on the experimental findings, a 3-stage mechanism for the initiation and growth of ECR is proposed.

Automatic analysis of the 3-D microstructure of fruit parenchyma tissue using X-ray micro-CT explains differences in aeration.

BACKGROUND: 3D high-resolution X-ray imaging methods have emerged over the last years for visualising the anatomy of tissue samples without substantial sample preparation. Quantitative analysis of cells and intercellular spaces in these images has, however, been difficult and was largely based on manual image processing. We present here an automated procedure for processing high-resolution X-ray images of parenchyma tissues of apple (Malus × domestica Borkh.) and pear (Pyrus communis L.) as a rapid objective method for characterizing 3D plant tissue anatomy at the level of single cells and intercellular spaces. RESULTS: We isolated neighboring cells in 3D images of apple and pear cortex tissues, and constructed a virtual sieve to discard incorrectly segmented cell particles or unseparated clumps of cells. Void networks were stripped down until their essential connectivity features remained. Statistical analysis of structural parameters showed significant differences between genotypes in the void and cell networks that relate to differences in aeration properties of the tissues. CONCLUSIONS: A new model for effective oxygen diffusivity of parenchyma tissue is proposed that not only accounts for the tortuosity of interconnected voids, but also for significant diffusion across cells where the void network is not connected. This will significantly aid interpretation and analysis of future tissue aeration studies. The automated image analysis methodology will also support pheno- and genotyping studies where the 3D tissue anatomy plays a role.

3D volumetric displacement and strain analysis of composite polymerization.

OBJECTIVE: The present study aimed at a better understanding of the internal shrinkage patterns within different cavity sizes. METHODS: Ten cylindrical cavities in two sizes were filled with a flowable composite and scanned using X-ray micro-computed tomography (µ-CT) before filling, before and after polymerization. Three-dimensional (3D) non-rigid image registration was applied to sets of two subsequent µ-CT images, before and after polymerization in order to calculate the displacements and strains caused by polymerization shrinkage. RESULTS: 3D volumetric displacement analysis disclosed a main vertical component for both the small and large cavities, however in the latter the downward direction reversed to an upward direction from a depth of approximately 2mm due to debonding at the bottom. Air bubbles and voids in the restorations increased upon polymerization, causing a reverse in strain in the surrounding areas. SIGNIFICANCE: Polymerization-induced shrinkage stress in composite restorations cannot be measured directly. This exploratory study revealed more information on cavity-size dependent shrinkage patterns and opens the way to more extensive studies using different composite materials and varying geometric cavity configurations.

Synchrotron X-ray computed laminography of the three-dimensional anatomy of tomato leaves.

Synchrotron radiation computed laminography (SR-CL) is presented as an imaging method for analyzing the three-dimensional (3D) anatomy of leaves. The SR-CL method was used to provide 3D images of 1-mm² samples of intact leaves at a pixel resolution of 750 nm. The method allowed visualization and quantitative analysis of palisade and spongy mesophyll cells, and showed local venation patterns, aspects of xylem vascular structure and stomata. The method failed to image subcellular organelles such as chloroplasts. We constructed 3D computer models of leaves that can provide a basis for calculating gas exchange, light penetration and water and solute transport. The leaf anatomy of two different tomato genotypes grown in saturating light conditions was compared by 3D analysis. Differences were found in calculated values of tissue porosity, cell number density, cell area to volume ratio and cell volume and cell shape distributions of palisade and spongy cell layers. In contrast, the exposed cell area to leaf area ratio in mesophyll, a descriptor that correlates to the maximum rate of photosynthesis in saturated light conditions, was no different between spongy and palisade cells or between genotypes. The use of 3D image processing avoids many of the limitations of anatomical analysis with two-dimensional sections.

Contrast-Enhanced Nanofocus X-Ray Computed Tomography Allows Virtual Three-Dimensional Histopathology and Morphometric Analysis of Osteoarthritis in Small Animal Models.

OBJECTIVE: One of the early hallmarks of osteoarthritis (OA) is a progressive degeneration of the articular cartilage. Early diagnosis of OA-associated cartilage alterations would be beneficial for disease prevention and control, and for the development of disease-modifying treatments. However, early diagnosis is still hampered by a lack of quantifiable readouts in preclinical models. DESIGN: In this study, we have shown the potency of contrast-enhanced nanofocus x-ray computed tomography (CE-nanoCT) to be used for virtual 3-dimensional (3D) histopathology in established mouse models for OA, and we compared with standard histopathology. RESULTS: We showed the equivalence of CE-nanoCT images to histopathology for the modified Mankin scoring of the cartilage structure and quality. Additionally, a limited set of 3D cartilage characteristics measured by CE-nanoCT image analysis in a user-independent and semiautomatic manner, that is, average and maximum of the noncalcified cartilage thickness distribution and loss in glycosaminoglycans, was shown to be predictive for the cartilage quality and structure as can be evaluated by histopathological scoring through the use of an empirical model. CONCLUSIONS: We have shown that CE-nanoCT is a tool that allows virtual histopathology and 3D morphological quantification of multitissue systems, such as the chondro-osseous junction. It provides faster and more quantitative data on cartilage structure and quality compared with standard histopathology while eliminating user bias. CE-nanoCT thus should allow capturing subtle differences in cartilage characteristics, carefully mapping OA progression and, ultimately, asses the beneficial changes when testing a candidate disease-modifying treatment.

In-situ spectroscopic investigation of ultrasonic assisted unfolding and aggregation of insulin.

It is well-known that fibrillogenesis of proteins can be influenced by diverse external parameters, such as temperature, pressure, agitation or chemical agents. The present preliminary study suggests that ultrasonic excitation at moderate intensities has a significant influence on the unfolding and aggregation behaviour of insulin. Irradiation with an average sound intensity of even as low as 70mW/cm(2) leads to a lowering of the unfolding and aggregation temperature up to 7K. The effect could be explained by an increase of the aggregation kinetics due to ultrasonically induced acoustic micro-streaming in the insulin solution that most probably enhances the aggregation rate. The clear and remarkable effect at relatively low sound intensities offers interesting options for further applications of ultrasound in biophysics and biochemistry. On the other hand, a process that causes a change of kinetics equivalent to 7K also gives a warning signal concerning the safety of those medical ultrasonic devices that work in this intensity range.

The influence of mixing methods and disinfectant on the physical properties of alginate impression materials.

The aims of this in vitro study were to quantify the effect of manual versus automatic mixing and of using a disinfectant on mechanical properties of three different alginate impression materials. Two of the three alginates tested were especially developed for orthodontic use: Orthotrace® and Orthofine® while the third was a conventional alginate CA37FS®. Alginates were mixed by hand or automatically using a Cavex alginate mixer II®. Mixing was performed at room temperature using tap water. The material was allowed to set in a water bath at 35°C (±1°C), simulating intra-oral setting conditions, and half of the samples were disinfected before testing. For each tested material, 10 standardized samples were used. The disinfectant used was the CavexImpreSafe® that has a bactericide, virucide, and fungicide function. The specimens were exposed for 3 minutes in a 3% solution and were then tested according to the ISO 1563: 1990 (E) standard specifications. Descriptive statistics and three-way analysis of variance were performed, and a 5% significance level was used for statistical analysis. Evaluation of tensile strength and elastic recovery of different alginate samples, hand versus automatical mixing or disinfected versus not disinfected, resulted in significant differences for all materials except for Orthofine®. Considering detail reproduction, all three alginates evaluated reproduced the 50-µm line successfully without interruption. The mixing method can significantly affect the elastic recovery and tensile strength of the alginates tested while the effect of using a disinfectant is less explicit.

Constant strain rate and peri-implant bone modeling: an in vivo longitudinal micro-CT analysis.

BACKGROUND: Strain, frequency, loading time, and strain rate, among others, determine mechanical parameters in osteogenic loading. We showed a significant osteogenic effect on bone mass (BM) by daily peri-implant loading at 1.600µÎµ.s(-1) after 4 weeks. PURPOSE: To study the peri-implant osteogenic effect of frequency and strain in the guinea pig tibia by in vivo longitudinal micro-computed tomography (CT) analysis. MATERIAL AND METHODS: One week after implant installation in both hind limb tibiae, one implant was loaded daily for 10' during 4 weeks, while the other served as control. Frequencies (3, 10, and 30Hz) and strains varied alike in the three series to keep the strain rate constant at 1.600µÎµ.s(-1) . In vivo micro-CT scans were taken of both tibiae: 1 week after implantation but before loading (v1) and after 2 (v2) and 4 weeks (v3) of loading as well as postmortem (pm). BM (BM (%) bone-occupied area fraction) was calculated as well as the difference between test and control sides (delta BM) RESULTS: All implants (n=78) were clinically stable at 4 weeks. Significant increase in BM was measured between v1 and v2 (p<.0001) and between v1 and v3 (p<.0001). A significant positive effect of loading on delta BM was observed in the distal peri-implant marrow 500 Region of Interest already 2 weeks after loading (p=.01) and was significantly larger (11%) in series 1 compared with series 2 (p=.006) and 3 (p=.016). CONCLUSIONS: Within the constraints of constant loading time and strain rate, the effect of early implant loading on the peri-implant bone is strongly dependent on strain and frequency. This cortical bone model has shown to be most sensitive for high force loading at low frequency.

Surface Roughness and Morphology Customization of Additive Manufactured Open Porous Ti6Al4V Structures.

Additive manufacturing (AM) is a production method that enables the building of porous structures with a controlled geometry. However, there is a limited control over the final surface of the product. Hence, complementary surface engineering strategies are needed. In this work, design of experiments (DoE) was used to customize post AM surface treatment for 3D selective laser melted Ti6Al4V open porous structures for bone tissue engineering. A two-level three-factor full factorial design was employed to assess the individual and interactive effects of the surface treatment duration and the concentration of the chemical etching solution on the final surface roughness and beam thickness of the treated porous structures. It was observed that the concentration of the surface treatment solution was the most important factor influencing roughness reduction. The designed beam thickness decreased the effectiveness of the surface treatment. In this case study, the optimized processing conditions for AM production and the post-AM surface treatment were defined based on the DoE output and were validated experimentally. This allowed the production of customized 3D porous structures with controlled surface roughness and overall morphological properties, which can assist in more controlled evaluation of the effect of surface roughness on various functional properties.